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Ultrafast equilibrium and non-equilibrium chemical reaction dynamics probed with multidimensional infrared spectroscopy

2012; Taylor & Francis; Volume: 31; Issue: 3 Linguagem: Inglês

10.1080/0144235x.2012.716610

1366-591X

Jessica M. Anna, Carlos R. Baiz, Matthew R. Ross, Robert McCanne, Kevin J. Kubarych,

Atmospheric Ozone and Climate

Abstract Two-dimensional infrared (2D-IR) spectroscopy provides powerful tools to investigate chemical reaction dynamics in the condensed phase. Correlating excitation and detection frequencies grants access to structural and dynamical information that is hidden in a linear absorption spectrum. Low-barrier reactions naturally can occur on the picosecond time scale, and although they are too rapid to study using nuclear magnetic resonance spectroscopy, the intrinsic ultrafast time resolution of coherent 2D-IR spectroscopy enables direct tracking of equilibrium reactive barrier crossings. 2D-IR chemical exchange spectroscopy can monitor the picosecond dynamics of non-triggered chemical reactions by correlating excited reactant frequencies with detected product frequencies. Solvent and temperature-dependent variations enable comparisons with microscopic rate theories at an unprecedented level of detail. 2D-IR spectroscopy is also emerging as a powerful probe of non-equilibrium light-driven chemical transformations. Transient 2D-IR spectroscopy is able to follow nascent photoproducts caused by electronic excitation or by a temperature jump. Soon it will be possible to study transient species with the full range of 2D observables, such as line shapes and waiting-time dynamics that have motivated the wide adoption of equilibrium 2D-IR spectroscopy. This review summarises the general progress in using 2D-IR spectroscopy to study chemical reactions in solution, focusing on our investigations into reactions of isomerisation of CO2(CO)8, photodissociation of Mn2(CO)10, geminate rebinding in [CpMo(CO)3]2 and charge transfer in betaine-30 as viewed from the first solvation shell. Keywords: multidimensional spectroscopyreaction dynamicsactivated barrier crossingphotolysisgeminate rebindingsolvation dynamicscharge transfer Acknowledgements The authors thank all the graduate students and postdoctorates of the Kubarych group, past and present, who have helped to make this study possible: Matthew Nee, Derek Osborne, John King, Evan Arthur, Aaron White, Josef Dunbar and Laura Kiefer. We have benefited from extremely fruitful collaborations with our colleagues Profs Eitan Geva and Barry Dunietz. This research has been supported by the National Science Foundation (CHE-0748501), the NSF Physics Frontiers Center: Frontiers in Optical, Coherent and Ultrafast Science, the Petroleum Research Fund of the American Chemical Society, the Camille & Henry Dreyfus Foundation, the Rackham Graduate School of the University of Michigan and the Department of Chemistry of the University of Michigan.